Silt Fence Configured for Capturing Pollutants and Fabric Forming the Same

ABSTRACT

A composite silt fence configured for capturing pollutants in one embodiment comprises a silt fence fabric including i) a polymeric geotextile fabric particulate filtering layer defining the hydraulic flow capacity for the silt fence, ii) a pollutant capturing layer coupled to the polymeric geotextile fabric particulate filtering layer and configured to capture some select pollutants in water from flow that has passed through the polymeric geotextile fabric particulate filtering layer, and iii) a backing layer coupled to the pollutant capturing layer; and a plurality of stakes secured to the silt fence fabric at spaced locations. The silt fence fabric yields higher hydraulic flow than existing fence constructions with greater sediment retention and pollutant containment features.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Pat. Application Serialnumber 16/207,610 filed Dec. 3, 2018 which published May 16, 2019 asPublication No. US 2019-0145068 and issued Oct. 11, 2022 as U.S. Pat.No. 11,466,413, which publication and application are incorporatedherein by reference.

U.S. Pat. Application Serial No. 16/207,610 is a continuation ofInternational Patent Application Serial Number PCT/US17/37563 filed Jun.14, 2017 and published Dec. 21, 2017 as WO 2017-218711, whichpublication is incorporated herein by reference. International PatentApplication Serial Number PCT/US17/37563 claims the benefit of U.S.Provisional Pat. Application Serial No. 62/349,890, entitled “Silt FenceConfigured for Capturing Pollutants”, filed on Jun. 14, 2016, which isincorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to silt fences, more specifically to asilt fence capturing pollutants from storm water and fabric forming thesame.

2. Description of Related Art

A silt fence, sometimes called a “filter fence,” is a temporary sedimentcontrol device used on construction sites to protect water quality innearby streams, rivers, lakes and seas from sediment (loose soil) instorm-water runoff. Silt fences are widely used on construction sites inNorth America and elsewhere, due to their low cost and simple design.

Silt fences are often perimeter controls and a typical fence consists ofa piece of synthetic filter fabric (also called a geotextile) stretchedbetween a series of wooden or metal fence stakes along a horizontalcontour level. The stakes are generally installed on the downhill sideof the fence, except sometimes at overlapping silt fence sections, andthe bottom edge of the fabric can be trenched into the soil.

Hanes Geo Components manufactures a representative sample ofcommercially available silt fence geotextiles, such as the TERRATEX®SF-50, TERRATEX® SF-90, TERRATEX® SF-D, and NTPEP brands which generallyare woven geotextiles made up of woven polypropylene filaments that areconsidered non-biodegradable and resistant to most soil chemicals,acids, and alkali with a pH range of 3 to 12.

In general, each state Department of Environmental Protection or similaragency will define the particulars for the silt fence in thatjurisdiction, often in a “Best Management Practices for Erosion andSedimentation Control” entitled regulation. These particulars includeminimum requirements for the fabric (strength, lifespan, flowrate,materials, etc), height requirements for the fences and stakes,material, size and spacing requirements for the stakes, etc.

The patent literature discusses and describes the state of the art insilt fence construction, as well as including some proposals that havenot been commercially viable. See for example U.S. Pat. Nos. 4,756,511,5,660,505, 5,758,868, 6,053,665, 6,945,739, 7,008,143, 8,465,230 and8,747,027 which are incorporated herein by reference. Collectively thesepatents also give an acceptable overview of existing silt fencetechnologies.

U.S. Pat. No. 7,157,010 proposes an interesting silt fence constructionand discloses a polymeric flocculent infused silt fence assemblycomprising two opposing and attached geo-textile sheets, each adapted tofilter entrained non-colloidal particles and together encasing a layerof polymeric flocculent material. The polymeric flocculent materialpreferably comprises anionic polyacrylamide. As water flow is flowedthrough the first geo-fabric sheet any entrained non-colloidal particlesabove the mesh size are filtered. Then the polymeric flocculent materialcoagulates a portion of the colloidal particles and forms flocs in theflowing water and the second geo-fabric sheet filters remainingentrained non-colloidal particles, including the coagulated flocs. Theconcept of adding to the functional performance of the silt fence inthis application is desirable, but this implementation will haveblinding problems that undesirably interferes with the flowcharacteristics of the silt fence.

U.S. Publication 2014-0154018 and U.S. Pat. 7,465,129 (Now reissuenumber Re42,695) all disclose reinforced silt retention sheet andsystems for silt retention wherein the reinforced silt retention sheetincludes a non-woven fabric having a series of entangled polymer fiberswith a reinforcing material secured within the fabric. The resultantreinforced silt retention sheet further can have openings of a desiredsize to enable filtering of a flow of fluid passing through thereinforced silt retention sheet. Improving strength and flowcharacteristics of a silt fence is helpful but does not address the needfor removing pollutants from a water stream.

There is a need for a silt fence with improved silt fence fabrics andwhich provide for capturing pollutants from storm water.

SUMMARY OF THE INVENTION

The present invention provides a composite silt fence comprising aplurality of spaced stakes and a composite silt fence fabric coupled tothe stakes and configured for capturing pollutants within storm water.Using standard ASTM testing with 1645 LBS water with 105 LBS soil and250 mg/L Oil for 75 minutes test run followed by a 1645 LBS waterflushing run for 90 minutes the silt fence of the present inventionyields a soil retention after the test run of greater than 85%,preferably greater than 90% and more preferably greater than 92%. Inthis standardized testing the silt fence of the present invention yieldsa seepage rate after the test run of greater than 60%, preferablygreater than 65% and more preferably greater than 70%. In thisstandardized testing the silt fence of the present invention yields anoil retention rate after the test run of greater than 90%, preferablygreater than 95% and more preferably greater than 99%. In thisstandardized testing the silt fence of the present invention yields aseepage rate after the flushing run of greater than 70%, preferablygreater than 75% and more preferably greater than 80%. In thisstandardized testing the silt fence of the present invention yields anoil retention rate after the flushing run of greater than 85%,preferably greater than 90% and more preferably greater than 95%.

One aspect of the present invention provides a composite silt fence thatcomprises a silt fence fabric including i) a polymeric geotextile fabricparticulate filtering layer defining the hydraulic flow capacity for thesilt fence, ii) a pollutant capturing layer coupled to the polymericgeotextile fabric particulate filtering layer and configured to capturesome select pollutants in water that has passed through the polymericgeotextile fabric particulate filtering layer, and iii) a backing layercoupled to the pollutant capturing layer; and a plurality of stakessecured to the silt fence fabric at spaced locations.

In a preferred embodiment of the present invention the polymericgeotextile fabric particulate filtering layer is a non-wovenpolypropylene particulate filtering layer having at least a 2 ouncerating and the backing layer is a 200-300 g/m² polyethylene layer. Inone embodiment of the present invention the pollutant capturing layer isformed including a kenaf material of 1-25 mm thickness or 60-80 gram/sq.ft.

The composite silt fence according to the present invention may providewherein the silt fence fabric has a width of 20"-48", preferably 26"-40"and most preferably 30"-36". Further the composite silt fence accordingto the present invention is preferably rollable, namely that the siltfence fabric, with or without the stakes, can be rolled into a coiledpack for shipping, delivery and installation.

The composite silt fence according to the present invention may providethat the pollutant capturing layer is configured to capture throughabsorption or adsorption at least one of hydrocarbons, heavy metals,phosphates, volatile organic compounds (VOCs), trichlorobenzenes (TCB),nitrates, arsenic, mercury, mineral oil, oil, polychlorinated biphenyls(PCBs), non-aqueous phase liquids (NAPLs), and polycyclic aromatichydrocarbons (PAH). The composite silt fence according to the presentinvention may provide that the pollutant capturing layer includes one ofactivated carbon, calcium phosphate and oil absorbing polymers. Thecomposite silt fence according to the present invention may provide thatthe pollutant capturing layer includes a hydrophobic oil absorbingpolyolefin.

The silt fence according to an alternative embodiment of the presentinvention provides a composite silt fence that comprises a silt fencefabric including i) a woven polymeric geotextile fabric particulatefiltering layer defining the hydraulic flow capacity for the silt fence,ii) a pollutant capturing layer coupled to the polymeric geotextilefabric particulate filtering layer and configured to capture throughabsorption or adsorption some select pollutants in water that has passedthrough the polymeric geotextile fabric particulate filtering layer, andiii) a woven polymeric geotextile fabric backing layer coupled to thepollutant capturing layer; and a plurality of stakes secured to the siltfence fabric at spaced locations. The woven polymeric geotextile fabricparticulate filtering layer and the woven polymeric geotextile fabricbacking layer of the silt fence fabric may include warp and weft threadswherein the warp threads extend substantially longitudinally along siltfence fabric while the weft threads extend generally perpendicular tothe silt fence fabric and wherein the woven polymeric geotextile fabricparticulate filtering layer and the woven polymeric geotextile fabricbacking layer of the silt fence fabric are formed of a polyolefin or apolyamide material. The composite silt fence according to thisembodiment of the present invention may provide that the pollutantcapturing layer is thermally bonded to the woven polymeric geotextilefabric filtering layer and to the woven polymeric geotextile fabricbacking layer.

One aspect of the invention provides a composite silt fence fabricconfigured to be coupled to stakes to form a composite silt fence, thefabric comprising: a polymeric geotextile fabric particulate filteringlayer extending an entire width and length of the composite silt fencefabric and defining a hydraulic flow capacity for the silt fence; apollutant capturing layer coupled to the polymeric geotextile fabricparticulate filtering layer and extending the entire width and length ofthe composite silt fence fabric so as to entirely overlay the polymericgeotextile fabric particulate filtering layer and configured to capturesome select pollutants in water from flow that has passed through thepolymeric geotextile fabric particulate filtering layer; and a backinglayer coupled to the pollutant capturing layer extending the entirewidth and length of the composite silt fence fabric so as to entirelyoverlay the pollutant capturing layer.

One aspect of the invention provides A composite silt fence comprising:a plurality of spaced staked; a composite fabric coupled to the stakes,the fabric comprising: i) a polymeric geotextile fabric particulatefiltering layer extending an entire width and length of the compositesilt fence fabric and defining a hydraulic flow capacity for the siltfence; ii) a pollutant capturing layer coupled to the polymericgeotextile fabric particulate filtering layer and extending the entirewidth and length of the composite silt fence fabric so as to entirelyoverlay the polymeric geotextile fabric particulate filtering layer andconfigured to capture some select pollutants in water from flow that haspassed through the polymeric geotextile fabric particulate filteringlayer; and iii) a backing layer coupled to the pollutant capturing layerextending the entire width and length of the composite silt fence fabricso as to entirely overlay the pollutant capturing layer.

A composite silt fence comprising: a plurality of spaced staked; acomposite fabric coupled to the stakes, the fabric including: i) apolymeric geotextile fabric particulate filtering layer extending anentire width and length of the composite silt fence fabric and defininga hydraulic flow capacity for the silt fence; ii) a pollutant capturinglayer coupled to the polymeric geotextile fabric particulate filteringlayer and extending the entire width and length of the composite siltfence fabric so as to entirely overlay the polymeric geotextile fabricparticulate filtering layer and configured to capture some selectpollutants in water from flow that has passed through the polymericgeotextile fabric particulate filtering layer; and iii) a backing layercoupled to the pollutant capturing layer extending the entire width andlength of the composite silt fence fabric so as to entirely overlay thepollutant capturing layer, wherein the polymeric geotextile fabricparticulate filtering layer and the pollutant capturing layer and thebacking layer are needle punched together.

These and other advantages of the present invention will be clarified inthe detailed description of the preferred embodiments taken togetherwith the associated figures.

BIREF DESCRIPTION OF THE FIGURES

FIG. 1 schematically illustrates a silt fence configured for capturingpollutants according to one aspect of the present invention;

FIG. 2 is a sectional schematic side view of a composite silt fencefabric used in the silt fence of FIG. 1 ; and

FIG. 3 is a schematic sectional side view of the silt fence of FIG. 1 .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is noted that, as used in this specification and the appended claims,the singular forms “a,” “an,” and “the” include plural referents unlessexpressly and unequivocally limited to one referent. The variousembodiments and examples of the present invention as presented hereinare each understood to be non-limiting with respect to the scope of theinvention.

One aspect of the present invention provides a composite silt fence 10that comprises a silt fence fabric 20 including: i) a polymericgeotextile fabric particulate filtering layer 22 defining the hydraulicflow capacity for the silt fence 10, ii) a pollutant capturing layer 24coupled to the polymeric geotextile fabric particulate filtering layer22 and configured to capture some select pollutants in water from flow 5that has passed through the polymeric geotextile fabric particulatefiltering layer 22, and iii) a backing layer 26 coupled to the pollutantcapturing layer; and a plurality of stakes 26 secured to the silt fencefabric 20 at spaced locations via staples 30 or similar fasteners.

The stakes 28 of the silt fence 10 of the present invention arepreferably formed of hardwood, or possibly metal (steel), and the fabric20 is “stakeable” in that it can be attached to these stakes 28 byconventional methods, preferably staples 30 (staples, zip-ties, and thelike). The composite silt fence fabric 20 is rollable, meaning that thefabric 20 can be rolled for shipping and installation, both with andwithout the stakes 28 attached.

In a preferred embodiment of the present invention the polymericgeotextile fabric particulate filtering layer 22 is a non-wovenpolypropylene particulate filtering layer having a 2-6 ounce rating. Thenon-woven polypropylene particulate filtering layer 22 promotes couplingof the layers 22, 24 And 26 together through needle punching. A“nonwoven” is a sheet, web, or batt of natural and/or man-made fibers orfilaments, typically excluding paper, that have not been converted intothe yarns, and that are bonded together in different ways (sometimesalso called Shaped Fabrics or Yarn free Fabrics). Needle punching is anonwoven process by which the fibers of one layer, 22, 24 or 26 aremechanically entangled to produce a coupled structure by repeatedpenetration of barbed needles through layers 22, 24 and 26. Specificallya needle board is mounted on a beam which is given an up and downreciprocating motion resulting in mechanically interlocked fibers,thereby providing the mechanical strength to the coupled layers to formthe fabric 20.

The non-woven polypropylene particulate filtering layer 22 defines thehydraulic flow capacity for the silt fence 10, defining the lowesthydraulic flow of the layers 22, 24 and 26. Hydraulic flow is sometimesreferenced by a “mesh size” which would define a given hydraulic flowunder given fixed conditions. In this context the non-wovenpolypropylene particulate filtering layer 22 will have the lowest meshsize of the layers 22, 24 and 26. In other words the remaining layers 24and 26 will not blind the fabric 10 in operation.

Each layer 22, 24 and 26 of the fabric has a purpose and the resultingfabric 20 as a specific preferred operational direction, namely theparticulate filtering layer 22 should face the incoming water flow 5 asshown. This differs from conventional single layer silt fence structureswhich are omnidirectional.

The non-woven polypropylene particulate filtering layer 22 can easilyadd color, such as part of the binding material forming the layer 22,such that it can have a contrasting color than the backing layer 26. Thedistinct coloring of the layer 22 and layer 26 will give a visualindication to the installers for proper orientation. A bright orange isa preferred color choice for the layer 22 as in addition to providing avisual cue for proper installation, post installation this color willgive an easily observed visual indication to operators within theconstruction site that they are approaching the silt fence 10, whichfences are typically installed at the perimeter of site and/or aroundother areas of erosion control issues.

In a preferred embodiment of the present invention, the backing layer 26is a 200-300 g/m² polyethylene layer. The backing layer 26 addsstructural support to the fabric 20 and encapsulates the layer 24allowing for wider variations for the layer 24 such as providing for abroader range of other additives that can be added in the layer 24. Thebacking layer 26 does not limit the hydraulic flow of the fabric 20 andalso allows for staples 30, alone, to be effectively used to couple thefabric 20 to the stakes 28. Prior art fences often require theadditional lath member to be used, which can also be used with the siltfence 10 of the invention but are not required. The backing layer 22 caneasily add color mainly for branding and such that it can have acontrasting color than the particulate filter layer 22 for properproduct orientation in the field.

The pollutant capturing layer 24 is generally configured to capturethrough absorption or adsorption. Adsorption is the adhesion of atoms,ions, or molecules from a gas, liquid, or dissolved solid to a surface.This process creates a film of the adsorbate on the surface of theadsorbent. This process differs from absorption, in which a fluid (theabsorbate) is dissolved by or permeates a solid, or liquid (theabsorbent), respectively. Adsorption is a surface-based process whileabsorption involves the whole volume of the material. Adsorption is asurface phenomenon.

The pollutant capturing layer 24 may be specifically configured tocapture at least one of hydrocarbons, heavy metals, phosphates, volatileorganic compounds (VOCs), trichlorobenzenes (TCB), nitrates, arsenic,mercury, mineral oil, oil, polychlorinated biphenyls (PCBs), non-aqueousphase liquids (NAPLs), and polycyclic aromatic hydrocarbons (PAH). Inone embodiment of the present invention the pollutant capturing layer isformed including a kenaf material of 1-25 mm thickness or 60-80 gram/sq.ft., such as is available from Kengo Corporation.

The pollutant capturing layer 24 may include one of activated carbon,calcium phosphate and oil absorbing polymers. Suitable construction ofthe pollutant capturing layer 24 can also follow the construction ofwater purifying geotextiles such as available from Huesker under theTEKOSEAL® brands.

The pollutant capturing layer 24 may also include includes a hydrophobicoil absorbing polyolefin, such as developed at Penn State University andlicensed under the PETROGEL™ mark. The PETROGEL™ technology offers highoil-absorption capability, no water absorption, fast kinetics, easyrecovery from the water’s surface, and cost-effectiveness.

The pollutant capturing layer 24 is formed with a hydraulic flow rate,calculated after the containment layer 24 is at full carrying capacity,larger than flow rate of the particulate filtering layer 22. Thepollutant capturing layer 24 will have an effective mesh opening sizedefining flow rate, calculated after the pollutant capturing layer 24 isat full carrying capacity, larger than the effective mesh size of thepolymeric geotextile fabric particulate filtering layer 22.

The silt fence fabric 20 has a width of 20"-48", preferably a width of26"-40" and most preferably a width of 30"-36". The width of the fabric20 is measured along the length of the stakes 28 along what is theheight of the fence 10.

The wooden stakes 28 generally have a length of 26"-60", preferably30"-48", and more preferably 36"-48". Metal stakes 28 may be used withalternative fastening methods other than the staples 30, but woodenstakes 28 are cost effective and allow for use of the staples 30 as asimple coupling mechanism.

The silt fabric 20 and silt fence 10 of the present invention can beinstalled in the same manner as all of the prior art silt fencestructures as shown in FIGS. 1 and 3 , wherein the stakes extend about 1foot into the ground and about 2 feet above and the fabric 20 extendinginto a backfilled 8-12" trench. The specific details of installation ofthe fence 10 such as regarding depth of stakes 28, height above grade ofthe fabric 20, the depth and width of the trench 35, length of fabric 20extending into the trench 35, and spacing of the stakes 28 may vary fromjurisdiction to jurisdiction and the needs of the particular site andare generally known in the art. The composite silt fence 10 withpollutant capturing layer 24 according to the present invention willremove pollutant in water similar in practice to that found with filtersocks.

A preferred silt fence 10 of the present invention was tested usingstandard ASTM testing (as of the earliest priority date of thisapplication), with the fence fabric 20 having the polymeric geotextilefabric particulate filtering layer 22 formed a a non-woven polypropyleneparticulate filtering layer 22 having a 2-6 ounce rating and the backinglayer 26 formed as a 200-300 g/m² polyethylene layer 26 and thepollutant capturing layer 24 formed including a kenaf material of 1-25mm thickness or 60-80 gram/sq. ft. The ASTM testing was performed underthe ASTM D 6459 Standard Test Method for Determination of Rolled ErosionControl Product (RECP) Performance in Protecting Hillslopes fromRainfall and Erosion, with the testing protocol that was in effect as ofFebruary 2017. Specifically the standard ASTM testing was performed with1645 LBS water with 105 LBS soil and 250 mg/L Oil for 75 minutes testrun followed by a 1645 LBS water flushing run for 90 minutes. The siltfence 10 of the present invention yields a soil retention after the testrun of greater than 85%, preferably greater than 90% and more preferablygreater than 92%, with test results of 92.31% being observed. In thisstandardized testing the silt fence 10 of the present invention yields aseepage rate after the test run of greater than 60%, preferably greaterthan 65% and more preferably greater than 70%, with test results of70.91% being observed. In this standardized testing the silt fence 10 ofthe present invention yields an oil retention rate after the test run ofgreater than 90%, preferably greater than 95% and more preferablygreater than 99%, with test results of 99.29% being observed. In thisstandardized testing the silt fence 10 of the present invention yields aseepage rate after the flushing run of greater than 70%, preferablygreater than 75% and more preferably greater than 80%, with test resultsof 81.09% being observed. In this standardized testing the silt fence 10of the present invention yields an oil retention rate after the flushingrun of greater than 85%, preferably greater than 90% and more preferablygreater than 95%, with test results of 96.78% being observed.

An alternative embodiment to the above described preferred embodimentprovides silt fence 10 configured for capturing pollutants from stormwater and one embodiment comprising a composite silt fence fabric 20including i) a woven polymeric geotextile fabric particulate filteringlayer 22 exhibiting the minimum mesh size of the silt fence; ii) apollutant capturing layer 24 (also called a contaminant capturing layer)thermally bonded to the woven polymeric geotextile fabric filteringlayer 22 and configured to capture through absorption or adsorption someselect pollutants in water that has passed through the woven polymericgeotextile fabric layer; and iii) a woven polymeric geotextile fabricbacking layer 26 bonded to the pollutant capturing layer 24 and having amesh size greater than the filtering layer mesh size; and a plurality ofstakes 28 secured to the silt fence fabric at spaced locations. Thewoven polymeric geotextile fabric particulate filtering layer 22 mayincludes warp and weft threads wherein the warp threads extendsubstantially longitudinally along the silt fence fabric, while the weftthreads extend generally perpendicular to the longitudinal axis orgenerally aligned with the axis of the stakes 28. The woven polymericgeotextile fabric particulate filtering layer 22 of the invention beeffectively formed using warp knitting technology on a RASCHELL™ WarpKnitted Double Needle Bar Machine. The woven polymeric geotextile fabricparticulate filtering layer 22 is preferably formed in this alternativeembodiment of a polyolefin or a polyamide material suitable for warpknitting technology and suitable to form an acceptable silt fence.

In the alternative embodiment the woven polymeric geotextile fabricparticulate filtering layer 22 also forms the particulate filtering orsediment filtering for the silt fence 10 of the invention. The mesh sizeof the woven polymeric geotextile fabric particulate filtering layer 22will be the smallest of the silt fence fabric 20 and may be selectedbased upon the requirements of the particular jurisdictions in which thesilt fence 10 is to be utilized. The woven polymeric geotextile fabricparticulate filtering layer 22 faces the water flow and thus thesediment is prevented from reaching the remaining layers 24 and 26 ofthe silt fence fabric.

The composite silt fence 10 according to the alternative embodiment ofthe invention includes the woven polymeric geotextile fabric backinglayer 26 discussed above. This layer 26 is for structural support and toprotect the pollutant capturing layer 24 of the silt fence fabric 20.This woven polymeric geotextile fabric layer 26 may be formed analogousto the filter layer 22 discussed above and may include warp and weftthreads wherein the warp threads extend substantially longitudinallyalong silt fence fabric 20 while the weft threads extend generallyperpendicular to the silt fence fabric 20. The woven polymericgeotextile fabric backing layer 26 of the silt fence fabric 20 may alsobe formed of a polyolefin or a polyamide material. As this layer 26 isonly for structure the mesh opening of the woven polymeric geotextilefabric backing layer 26 is larger than the woven polymeric geotextilefabric particulate filtering layer 22.

In this alternative embodiment the pollutant capturing layer 24 isbonded to the woven polymeric geotextile fabric filtering layer 22 andto the woven polymeric geotextile fabric backing layer 26 in aconventional fashion, such as adhesives or thermal bonding. Thermalboding is easy and avoids separate adhesive materials that could disruptperformance of the fabric 20.

A further alternative embodiment of the present invention is a singlelayer fabric 20 which utilizes the material forming the pollutantcapturing layer 24 described above to form a single mesh layer whereinthe mesh opening acts as the particulate filter and the material acts asthe pollutant capturing element as well. Specifically a geotextilefabric particulate filtering layer using warp and weft threads asdiscussed above, where the material forming the pollutant capturinglayer discussed above is used to form one or more of the weft threads.

The present invention has been described with reference to specificdetails of particular embodiments thereof. It is not intended that suchdetails be regarded as limitations upon the scope of the inventionexcept insofar as and to the extent that they are included in theaccompanying claims. A number of variations to the present inventionwill be apparent to those of ordinary skill in the art and thesevariations will not depart from the spirit and scope of the presentinvention. The scope of the invention is defined by the appended claimsand equivalents thereto.

We claim:
 1. A composite silt fence fabric configured to be coupled tostakes to form a composite silt fence, the fabric comprising: apolymeric geotextile fabric particulate filtering layer extendingsubstantially an entire width and length of the composite silt fencefabric and defining a hydraulic flow capacity for the silt fence; apollutant capturing layer coupled to the polymeric geotextile fabricparticulate filtering layer and extending substantially the entire widthand length of the composite silt fence fabric so as to substantiallyentirely overlay the polymeric geotextile fabric particulate filteringlayer and configured to capture some select pollutants in water fromflow that has passed through the polymeric geotextile fabric particulatefiltering layer; and a backing layer coupled to the pollutant capturinglayer extending substantially the entire width and length of thecomposite silt fence fabric so as to substantially entirely overlay thepollutant capturing layer.
 2. The composite silt fence fabric accordingto claim 1 wherein performing standard ASTM testing on a silt fenceformed with the composite silt fence fabric with 1645 LBS water with 105LBS soil and 250 mg/L Oil for a 75 minutes test run yields a soilretention after the test run of greater than 85%.
 3. The composite siltfence fabric according to claim 2 wherein the test run yields a soilretention after the test run of greater than 90%.
 4. The composite siltfence fabric according to claim 1 wherein performing standard ASTMtesting on a silt fence formed with the composite silt fence fabric with1645 LBS water with 105 LBS soil and 250 mg/L Oil for a 75 minutes testrun yields a seepage rate after the test run of greater than 60%.
 5. Thecomposite silt fence fabric according to claim 4 wherein the test runyields a seepage rate after the test run of greater than 65%.
 6. Thecomposite silt fence fabric according to claim 1 wherein performingstandard ASTM testing on a silt fence formed with the composite siltfence fabric with 1645 LBS water with 105 LBS soil and 250 mg/L Oil fora 75 minutes test run yields an oil retention rate after the test run ofgreater than 90%.
 7. The composite silt fence fabric according to claim6 wherein the test run yields an oil retention rate after the test runof greater than 95%.
 8. A composite silt fence comprising: a pluralityof spaced stakes; and a composite fabric coupled to the stakes, thefabric including: i) a polymeric geotextile fabric particulate filteringlayer extending substantially an entire width and length of thecomposite silt fence fabric and defining a hydraulic flow capacity forthe silt fence; ii) a pollutant capturing layer coupled to the polymericgeotextile fabric particulate filtering layer and extendingsubstantially the entire width and length of the composite silt fencefabric so as to substantially entirely overlay the polymeric geotextilefabric particulate filtering layer and configured to capture some selectpollutants in water from flow that has passed through the polymericgeotextile fabric particulate filtering layer; and iii) a backing layercoupled to the pollutant capturing layer extending substantially theentire width and length of the composite silt fence fabric so as tosubstantially entirely overlay the pollutant capturing layer.
 9. Thecomposite silt fence according to claim 8 wherein the polymericgeotextile fabric particulate filtering layer is a non-wovenpolypropylene particulate filtering layer having at least a 2 ouncerating.
 10. The composite silt fence according to claims 8 wherein thebacking layer is a 200-300 g/m² polyethylene layer.
 11. The compositesilt fence according to claims 8 wherein the pollutant capturing layeris formed including a kenaf material and wherein the backing layer is a200-300 g/m² polyethylene layer.
 12. The composite silt fence accordingto claim 11 wherein the pollutant capturing layer is at least one of1-25 mm in thickness or 60-80 gram/sq. ft.
 13. The composite silt fenceaccording to claim 12 wherein the layers of the silt fence fabric areneedle punched together.
 14. The composite silt fence according to claim8 wherein the silt fence fabric has a width of 20"-48" and is rollable.15. The composite silt fence according to claim 8 wherein the pollutantcapturing layer is thermally bonded to the polymeric geotextile fabricfiltering layer.
 16. A composite silt fence comprising: a plurality ofspaced stakes; and a composite fabric coupled to the stakes, the fabricincluding: i) a polymeric geotextile fabric particulate filtering layerextending substantially an entire width and length of the composite siltfence fabric and defining a hydraulic flow capacity for the silt fence;ii) a pollutant capturing layer coupled to the polymeric geotextilefabric particulate filtering layer and extending substantially theentire width and length of the composite silt fence fabric so as tosubstantially entirely overlay the polymeric geotextile fabricparticulate filtering layer and configured to capture some selectpollutants in water from flow that has passed through the polymericgeotextile fabric particulate filtering layer; and iii) a backing layercoupled to the pollutant capturing layer extending substantially theentire width and length of the composite silt fence fabric so as tosubstantially entirely overlay the pollutant capturing layer, whereinthe polymeric geotextile fabric particulate filtering layer and thepollutant capturing layer and the backing layer are needle punchedtogether.
 17. The composite silt fence according to claim 16 wherein thepollutant capturing layer is 1-25 mm in thickness.
 18. The compositesilt fence according to claim 16 wherein the pollutant capturing layeris 60-80 gram/sq. ft.
 19. The composite silt fence according to claim 18wherein performing standard ASTM testing on the silt fence with 1645 LBSwater with 105 LBS soil and 250 mg/L Oil for a 75 minutes test runyields a yields an oil retention rate after the test run of greater than90%.
 20. The composite silt fence according to claim 19 wherein the testrun yields an oil retention rate after the test run of greater than 95%.